1. Field of the Invention
The present invention relates to improvements in hand tools and more particularly it relates to an improved powered actuator system for trigger-operated hand tools. Still more particularly, but without limitation, the invention is concerned with providing an improved powered actuator system which is suitable for use with hand-held tagging tools or other trigger-operated hand tools whose repeated use can strain or injure (temporarily or permanently) the operator's hand.
2. The Prior Art
Lightweight, pistol-like hand tools are widely used to fasten labels to a variety of products. A fastener is ejected from a barrel by means of a large trigger which is typically spring-loaded to provide the energy to drive fasteners out of the barrel. Such hand tools are loosely, but extensively, called "handguns" or "guns".
Plastics-material fasteners having a closable barb at one end, a thin shank and an anchor at the other end, often referred to simply as "barbs", are widely used for attaching price or product-information labels to garments, soft furnishings and many other high-volume consumer products. A standard technique for attaching them involves "firing" or urging the barbs through a price or product label held in front of an attachment point on the garment or other product, by means of a pistol-like hand-held applicator tool which discharges a "collapsed" or closed barb through a hollow needle projecting from the barrel of the applicator. In those instances where the label or tag is pre-punched with a hole, the needle is placed through this hole and the label or tag is held by the operator's forefinger just prior to inserting the needle through the garment layer to which it is to be attached. The barbed end of the fastener penetrates the label and garment, draws the fastener shank through the label and garment, and opens up on the other side of the garment so that the barb cannot be drawn back through the garment. Meanwhile the fastener anchor, which can be a simple T-shaped piece, prevents the shank from passing through the label. In this manner the fastener (sometimes referred to as a barb) is secured to the garment so that its removal leaves visible evidence: usually the barb is severed, and the alternatives are to cut or tear the garment or label.
Typical tagging tools are trigger-operated hand tools of the type having a barrel adapted to lie across an operator's hand, an operating head at one end of the barrel, a hand-grip-and-trigger assembly depending from the barrel and configured to be held in one hand between the fingers and palm thereof so that the tool can be operated by squeezing the trigger, wherein the required squeeze loading is in excess of 2 lb. For tagging with barbs, a hollow applicator needle is mounted in the barrel of the tool and is fed with a skein of barbs, in some instances from a magazine carried on the tool, one barb being fired each time the trigger is pulled. Since the energy driving the barb comes from the operator's hand, significant loading of the trigger is required, and typical actuator forces are in excess of 4 or 6 lb., and commonly range from four to eight pounds only because ten pounds would be too heavy for most operators.
Long-term repetitive use of these tools, as is required for commercial and industrial applications, can cause carpal tunnel syndrome, a disorder of the nervous system in the heel of the hand which may substantially disable the operator's hand. The disablement can often last weeks or months and in severe cases may be permanent. Obviously, there is a need to provide tagging equipment which is not prone to cause such a debilitating syndrome.
To this end the prior art has provided powered actuator systems for trigger-operated hand tools which mount the tool in a stand at a table and in which a power-driven mechanical linkage operates the trigger under the control of a hand or foot switch. These systems can relieve the operator of undue and potentially injurious stresses, but require that the product to be tagged be brought to the tagging table (or vice versa), which restricts the utility of this type of tagging system. In particular, such an immobile or inflexible tagging system is plainly incapable of being easily manipulated for use in tagging boxed or hanging garments.
Hand-held powered tagging tools are known but they tend to be bulky and expensive. These tools also have a variety of designs serving a variety of special needs and duplication of this variety in a range of powered tools would be impractical and costly either for the manufacturer of the equipment or its customers. Furthermore, prior art powered portable tools are heavy and cumbersome.
There is accordingly a need to provide an improved powered actuator system which can overcome the drawbacks of the prior art. Both electric and pneumatic power means have been proposed, but neither has been satisfactorily incorporated in a system that can fulfill the objects of the present invention.
A prior art design which has come to the applicant's attention is the HT-100 device. This design, which makes use of the HT-100 booster shown at the bottom of the page, can be operated by closing port "D" by "finger" pressure instead of by using a hair-trigger valve. However, the leakage rate of wasted air is very high, unless the air pressure is very low. Also, the HT-100 device would still require another valve to operate the cylinder which would thus necessitate a 4-way valve (double-acting cylinder).